http://www.tipplers.com/info/
http://www.tipplers.com/ftsofusa/
http://en.wikipedia.org/wiki/Tippler
Heres some links, halogan lights on your loft can keep them flying for a full 24 hour day, I dont know much about this method but there might be something in the links on this.
Site for show tipplers: http://www.national-federation.co.uk/
Hope that helps